fix(fusion_clock): tz resolver uses company.partner_id.tz (res.company has no tz in Odoo 19)

_resolve_tz fell back to env.company.tz, which raises AttributeError for any
user without a personal tz (surfaced by the new list-wide pay-period filters,
which resolve a company-level tz). Use env.company.partner_id.tz. Regression
test added. Bump 3.15.0 -> 3.15.1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

fusion_clock/__manifest__.py

@@ -5,7 +5,7 @@
 
 {
     'name': 'Fusion Clock',
-    'version': '19.0.3.15.0',
+    'version': '19.0.3.15.1',
     'category': 'Human Resources/Attendances',
     'summary': 'Complete Employee T&A with Geofencing, Shifts, Penalties, Overtime, Kiosk, Dashboard & Payroll Export',
     'description': """